Mac battery dies while asleep, I think due to Spotlight. How can I fix it?

Genius-Barré wrote:

I lose about 10% per hour while the lid is shut. I've tried everything I've seen online, including turning off power nap and wake with wifi, stopping notifications while asleep, turning off OneDrive syncing, resetting the SMC, and most of the other basic things I saw in previous threads. In the past 2 hours I lost 20% while it was closed, and the only thing taking significant power in the activity monitor is spotlight, and I haven't been using the computer at all the past few days so that seems to be the most likely culprit. I've had this computer for months, it's not indexing. How can I fix it?

My battery runtime is low

https://support.apple.com/en-us/HT204054#runtime

Try a safeboot to clear system cache files, reboot as normal to test—

 https://support.apple.com/en-us/HT201262